DE1097983B - Reaction device for carrying out photochemical chlorination processes - Google Patents

Description

GERMAN

The invention relates to a reaction device for carrying out photochemical chlorination processes, especially for addition chlorination of benzene, with practically parallel, translucent and interconnected pipes provided with cooling and lighting devices are, as well as with separate facilities for the introduction of the starting materials, and for the removal of the Reaction mixture.

It is known that the addition chlorination of benzene for the production of hexachlorocyclohexane in the presence of carbon tetrachloride and acetic anhydride at low temperatures.

The purpose of the invention is to provide a reaction device for carrying out photochemical Chlorination processes, which are particularly suitable for continuous work at low temperatures is determined and z. B. the continuous production of hexachlorocyclohexane using a Mixed solvents, such as acetic anhydride and carbon tetrachloride, with a substantial γ-isomer content allowed.

In particular, the invention aims to provide such a continuous reaction device Production of z. B. hexachlorocyclohexane, in which the simultaneous maintenance of a constant chlorine concentration and temperature in the entire reaction system is guaranteed, so that the formation of by-products is reduced to a minimum.

An apparatus for chlorinating benzene using ultraviolet light is known, in which the lighting device is arranged in one leg of a U-shaped reaction tube. The lower part of the U-shaped reaction tube is connected to a coolant. With the well-known The chlorine-benzene mixture is introduced into the apparatus only at one point in the circulation system Exposure to exposure, so that different concentrations of chlorine in the individual parts of the device are present even when the reaction mixture is constantly kept in circulation. The order the lighting device inside the reaction tube leads to particular difficulties with regard to the dissipation of the heat emitted by the lighting device.

An apparatus for carrying out chlorination reactions under ultraviolet radiation is also known, in which bundles of reaction tubes are connected in series and the starting materials are pressed through these tube bundles by means of pumps. Even with this apparatus, a constant chlorine concentration and reaction temperature cannot be obtained in the entire system, in particular not the reaction device for execution
photochemical chlorination processes

Applicant:

Stauffer Chemical Company,
San Francisco, Calif. (V. St. A.)

Representative: Dr. E. Wiegand, Munich 15,

and Dipl.-Ing. W. Niemann,
Hamburg 1, Ballindamm 26, patent attorneys

Claimed priority:
V. St. v. America September 11, 1956

Harold Mahonri Pitt, Torrance, Calif. (V. St. Α.),
has been named as the inventor

since the reaction mixture is drawn off and returned to the inlet only at individual points in the system will.

In the reaction device according to the invention, on the other hand, the cooling device is inside the Reaction tubes and the lighting device on the outside of the translucent reaction tubes arranged, wherein the reaction tubes are connected to a mixing chamber, which in their upper Part contains a multi-vane centrifugal pump rotor.

In a particular embodiment of the reaction device according to the invention are the device for introducing the starting materials and the device for withdrawing reaction mixtures at the lower end of the mixing chamber, wherein the inlet device is inserted further into the mixing chamber than the outlet device.

The invention is explained in more detail with reference to the drawing, for example.

Fig. 1 is a side view of the device, partly in section;

Figure 2 is a bottom plan view of the device of Figure 1;

Fig. 3 is a section on line 3-3 of Fig. 1 on an enlarged scale;

Fig. 4 is a section through one of the arms of the device on an enlarged scale;

Fig. 5 is a flow sheet for a process in which the apparatus according to the invention is particularly suitable.

109 507/515

3 4

The device shown has a central part with thiosulphate solution (a known method

112 with an inlet 113 for the introduction of driving). A steady chlorine concentration

Chlorine and benzene and a condition at the bottom of the middle part can also be achieved by a photoelectric cell

112 provided outlet 114 for the removal of a be brought about, which in turn reduces the speed

the liquid stream containing the product. The - 5 speed of the chlorine supply or the intensity of the lighting

upper end of the 'middle part 112 is a device with wings changes.

The reactor is driven by a pump rotor 116 which is provided via a line 13

a shaft 117 is located, which via a coolant supplied to it at the desired temperature

one end attached pulley 118 held by door. Chlorine is introduced through a line 16

a suitable power source (not shown) rotated io guided while the rotor provided with wings in the

can be. Reactor 12 is rotated to get a homogeneous mass in

A plurality of the reaction zone extends from the central part 112. Products made from number of separate, U-shaped legs, exit the reactor 12, go through a line indicated generally at 121; he is shown 17 to a secondary reactor 20 (a small ordered Embodiment are four such legs 15 container or vessel, the interior of which is exposed), where intended. However, if desired, the excess chlorine present can also be reduced to a trace or less, with the mini being led, and then through a line 25 to mum is of course a single leg. Each of these have a solvent preheater, generally at 18 U-shaped leg 121 has a designated. It is usually not necessary that upper strand 122 and a lower strand 123 to cool the 20 secondary reactor 20; has insulation a vertical line piece 124 with one another has generally proven to be sufficient. Somehow connected are. Each upper strand 122 is in which acetic anhydride, which is open to fill up Connection with the central part 112 is immediately required, is introduced into the line 25; it bar near the Punipen rotor 116 and is merely an addition of anhydride as a replacement usually liquid required by the central portion 25 of the one with the product removed 112 runs around. «* - - will and will relate to a little less than 1 percent by weight

Each of the strands 122 and 123 is made of glass of the product.

represents the rays of a suitable light source, attached to the solvent preheater 18 is a having z. B. lamps 125 (Fig. 4) to pass through. Packed column section 51 is provided, The lamps are about the longitudinal axis of each strand 30 of the at least one theoretical plate around at a distance from one another and is equivalent. Above the column 51 is a back stretch usually parallel to this axis; they are arranged flow condenser 19, which are a gas outlet from a suitable reflector housing 126 line 52 for the removal of hydrogen chloride and surround. any inert gas present. It will be enough

Since in general the addition chlorination of 35 heat is supplied to the preheater 18 to steady

Benzene should preferably be maintained in the column 51 at relatively low conditions.

Temperature, e.g. B. in the order of +5 to hold. Material from the heater 18 is over

-25 ° C, .are in each branch of the one line 22 under control by a valve 24

Legs 122 and 123 extending in a U-shape to a boiler 23. .

Silver tubes 127 arranged (Fig. 3), the ends of which with 40. If in the system the concentration of acetyl

Inlet lines 128 and outlet lines 129 chlorine with respect to acetic acid grows, one can

are bound to feed a small amount of water to the column 51 in order to circulate a suitable cooling agent

by means of each of the tubes 127. hydrolyze the acetyl chloride. In practice,

The application of the device according to the technical chlorine yields about 1 kg or more of water

Finding is below with reference to Fig. 5 45 per ton, and this is usually sufficient for

explains which shows a flow sheet of concern with the acetyl chloride-acetic acid balance

the practical implementation of the invention on conti- bear.

on a more precise basis can be used. With 6 is In the boiler 23 volatilized substances are above a reservoir for a solvent mixture discharged through a line 26, designated by a condenser. The storage container 6 is condensed by an additional 5 ° capacitor 27 and then fed into a receptacle of argon, helium or the like. Passed through a container 28, which has a barometric Line 7 on a leg 29 slightly above atmospheric pressure and a valve 31 with the storage container Pressure kept to oxygen from the ter 6 is connected. The receptacle 28 is Exclude solvent mixture. A benzene held under vacuum by a vacuum pump Feed line 8 is provided through which fresh 55 (not shown) is applied to a line Benzene is added to replace that connected to 32.

Forms hexachlorocyclohexane; the benzene can be connected to added to a suitable place and z. B. by device 33 under control by a valve 34 abzodie Line 25 are fed. Material from the gene and then fed into a vessel 36 from which the Storage container 6 is then lowered through a line 9 60 product via a valve 37 and a line 38 Control is drawn through valve 11 into the reactor. The solvent mixture is from the drawn, which is indicated generally at 12 and dem- vessel 36 through a steam line 39 in a cone is similar to the capacitor 41 with reference to FIGS. 1 to 4 and from there into a receptacle although carried out in the flow sheet of FIG. 42, which is maintained under vacuum, the Fig. 5 only a set of U-shaped legs 121 65 through a suitable vacuum pump (not shown) is shown. is applied to a line 43. From the recording

A steady state of chlorine concentration, which at container 42 is the solvent mixture by a

Working temperature is to be maintained, is withdrawn through line 44 with a valve 46 and into the

intermittent sampling of the reaction mass, transfer line 22 upstream of the valve 24 returned. This in with excess iodine ion and titration of the sample 70 in the receptacles 28 and 42

Claims (1)

5 6 The solvent mixture is in an oxygen-free atmosphere of the boiler via line 26 and the condenser sphere condensed. 27 was passed to the receptacle 28, the In the following, an example of an operation is maintained at a pressure of 120 ¹ to 200 mm Hg using a device according to the invention. The solvent mixture was dufch the finding given. 5 barometric legs 29 in the storage container 6 10.532 kg / hour of make-up benzene were returned to the. Reservoir 6 supplied while 8.9 l / minute The liquid collected in the boiler 23 was a benzene-acetic anhydride-carbon tetra- passed through the line 33 into the vessel 36 , from withdrawn chloride mixture and into the reactor 12 which the solvent mixture present through the were led. Furthermore, in the reactor 12, line 39 was removed into the receiving vessel 42. 29.066 kg / hour of chlorine introduced on a 39.340 kg / hour of the product from the Temperature of -1O ⁰ C was kept. The withdrawn from vessel 36 ; 11.030 kg of the product consisted the stream emerging from reactor 12 contained 2.13 g / l of that from the y-isomer of hexachlorocyclohexane, Free chlorine. The current was passed through the secondary which had a content of j'-isomers of 28.0 ¹⁰ / o reactor 20 led to the existing free chlorine 15 speaks. The receptacle 42 was under a further reduce by reaction with the benzene. absolute pressure maintained at 25 to 35 mm Hg. That The entire reaction mass flow, the benzene, hexa product, contained 0.314 kg of acetic anhydride; one chlorocyclohexane, carbon tetrachloride, acetic acid- equal amount of acetic anhydride was in each anhydride, acetic acid and acetyl chloride. Hour of the line 25 fed. The product withdrawn through line 38 was then fed into the solvent preheater 18 leads where the material is heated to a temperature liquid and had a temperature of 150 ° C. It which was above its boiling point at which it was vigorously stirred with water to remove traces of deten pressure, e.g. B. 92 ° C at atmospheric pressure was. to remove existing acetic anhydride and The composition of the current, with an infra, converting the material into fine globules, Determined by the red spectrophotometer, the volume was 25 The reactor described is, as can be seen, for percent: continuous chlorination of benzene to produce q yy _ _ g _? 2 supply of hexachlorocyclohexane with an increased C ° jj ⁶ Q 5.0 content of;> - isomer suitable. & Υο ^& οη :::::::::::::::::::::: ⁵ Ij ^ Patent claims: CH COCl 7.7 1st reaction device for performing photo- qq \ 18.8 chemical chlorination processes, especially for * ΤπηΊϊ addition chlorination of benzene, with practical parallel, translucent and among each other In the solvent preheater 18, Ben-35 connected pipes, which are provided with cooling and luminous zol, carbon tetrachloride, acetyl chloride and acetic acid, as well as with acid in the form of an azeotropic mixture, were volatilized into a separate device for the introduction of the off-distillation column, where the acetyl chloride gear fabrics and for withdrawing the reaction and the acetic acid under formation of acetic acid mixture, characterized in that the Kühlanhydrid and hydrochloric transpose. The attachment device (127) inside the reaction tubes hydride was returned to the preheater, and (121) and the lighting device (125) on the hydrogen chloride were removed through a gas line outside the reaction tubes (121) at the top. net and the reaction tubes (121) with a mixing In the example above, 0.145 kg / chamber (112) were connected to the upper one Hours of hydrogen chloride removed. Together they are part of a multi-vane centrifugal pump rotor settlement of the material which passed through the line 22 , (116) contains. was essentially the same as that of the ma- 2. Device according to claim 1, characterized geterials that occurred in the preheater 18, because the features in that the means for Einder column 51 caused change in the composi- lead of the starting materials (113 ) and the facility was too small to be measured by conventional analytical methods for removing reaction mixture (114). The effect of the heating and distillation stage located at the lower end of the mixing chamber can only be observed after the inlet device (113) into the mixing chamber has been worked for a long time, Distillation stage one direction,
gradual decrease in acetic anhydride concentration tion occurs while the concentration of acetyl. chloride and acetic acid grows. French Patent No. 1,066,893; The material in line 22 was obtained from British Patent No. 750502; Valve 24 led to the boiler 23 , where the solution U.S. Patents Nos. 1735 610, 2,656,313, medium mixture evaporated and from the top end 60 2 628 260, 2 622 105. 1 sheet of drawings © 109 507/515 1.61